UK businesses are on alert for the Code Red worm, which is set to reawaken between midnight and 1.00am tonight (UK time).
As many as 350,000 machines could already be infected by the worm, which is potentially capable of doing serious damage to the internet and causing UK computing to grind to a halt.
A joint advisory notice from the FBI's National Infrastructure Protection Center and the Critical Infrastructure Assurance Office warned that the infestation was continuing. "Mutations of the worm have already begun to appear, and the worm is timed to begin hyper-growth," the advisory said.
Security experts, however, are divided over the real threat posed by Code Red. Some are beginning to backtrack, saying that coverage of the virus has reached fever pitch and misinformation is spreading. Opinion is also split about the FBI warnings, which some experts claim have actually added to the problem.
"The Code Red worm is not as great a threat as some experts are implying," said Iain Franklin of security firm Entercept. He warned that, if security vendors continue to hype Code Red and disaster fails to strike, no one will listen when the next worm hits.
This view is shared by a number of other security watchers who feel that the worst could already be over. David Duke, of Cryptic Software, said that most businesses should have already updated their servers to defend against the worm.
"The scary thing about Code Red is its totally automated transport mechanism, not its payload," said Duke, suggesting that the coding techniques used to build the worm indicate future trends for more destructive viruses.